Indicating device for lecher systems



July s, 1941.

H. Bon-:RscH l INDICATING -DEVICE FOR LECHER SYSTEMS lllrl Filed April26', 1940 h, rx Or te DO eB Vm ma Patented' July s, 1941 UNITED" STATESPATIENT OFFICE INDICATING nEvIcE Fon Lacuna sYs'rEMs Hans Boersch,Berlin, Germany, assignor to General Electric Company, a corporation ofNew York Application April 26, 1940,seria1 No. 331,891

' Germany February 6, 1939 aclantis.- (ci. 177-311) I My inventionrelates to current indicating de vices and has for one of its' objectsthe provision of animproved arrangement for indicating current nodes andcurrent loops in lecher systems without drawing excessive energy fromthe system.

For the measurement of wave length in very high irequency electricallcircuits it has been customary to employ what are known asparallel-conductor systems or lecher wire systems vfor measuring theWave length. ,In these systems, the actual length of the half wave isphysically measured by measuring the distance between current nodes orcurrent loops inthe parallel -desent lamp is represented by `2. It is sodesigned that its two -leads loop each on one of the wires, so that acurrent flows throughthe incandescent lamp when the leads are notexactly at the position of current nodes of the wires l, v place at thepoint in question of the lecher system can be gathered from thebrightness of the incandescent lamp and'in thisway there canbe found themaxima and minima of this os-i cillation, that is, the current loops andthe cur` rent nodes. Bolometers and thermo-elements act in like manner.'I'he incandescent lamp and alsothe other instruments however have thedrawback that they take. away from the lecher system a comparativelylarge amount onenergy The intensity of the oscillation taking mercurousiodide-silver iodide, for example, which at about 45 C. changes itsyellow color If desired, some other member of Vthe copper' family in theperiodic varrangement into orange.

of elements may be substituted for the silver, 'lhus mercurousiodide-copper idide may be employed which changes at over '70 C. fromred .to black. Other compounds include arsenic- 4 antimony and lead asheat-indicating colors. 'Organic color changing substances which maybeemployed include a-phenyldiphenylene fulgide or a-diphenylene-diphenylfulgid, -Y of which the iirst'is dark red at room temperatureand is purple at temperatures between 54 and 152, whereas the second atroom temperature isBordeaux red and is dark blue at temperaturesbetween'l and 156 C. All these colors with which the rod serving for theindication can for` example be coated are reversible in 'theirthermo-chronic behavior, i. e. when a change o'f temperature is reversedthen the original shade of color appears. The color is therefore clearlydetermined by the temperature.V 'I'his latter property is to bepossessed by all the heat indicating colors coming into use within thescope of the invention.

The.invention 'wll be understood more readily from .the followingdetailed description when considered in connection with the accompanyingdrawing and those features of the invention which are .believed to benovel and patentable l. will be pointed out in the claims appendedhereto. i In the drawing, Fig. y1 isa schematic diagram in the form ofheat. It is for example necessary for the indication to heat theincandescent lilament of the lamp to about 600 C.

Inorder to obviate this drawback, according to the invention in itspreferred form there istofbe employed for the indication an electricallyconductive rod bridging over the lecher system and which is coated withone or more heat-indieating colors, the shade of which is clearly de.

termined by the temperature of the rod.

Heat indicating colors are characterized' by changing hue at de nitetemperatures. This property is shown by a double salt, such asillustrating a. lecher wire system of the type already known prior to myinvention. Fig. 2 is a schematic diagram illustrating an embodiment ofmy invention and showing the manner lin which current nodes are located;and Fig. 3 is a schematic diagram illustrating a modiiied form ofapparatus embodying my invention.

An example ofthe color changing property determined by temperature asset forth in. this in-. vention is shown in Fig. 2. In this, two lecherVwires are indicated by I, while 3 represents an indicating rod accordingto the invention. This rod is electrically and preferably metallicallyconductive, and is provided at least over one zone of its surface withan indicator color, the shade of which depends upon the temperature atwhich .the rod is heated on the passage ofthe current.

The positions of the current nodes of the lecher system are indicated by4,- 5,' 6, 1. The variation in current intensity along the lecher wiresis rep-- resented by the broken line curve Il, By means of the indicatorrod, according to the invention.

it is quite simple to determine the energy of ,the lecher system; itis'only necessary for this purpose to determine those consecutive points8 and 9 at which `a given change of color takes place in the one or inthe other sense, on the wire. From the distance apart of the two points8 and 9 at a given change in the color. compared with' the distancebetween the current nodes '5 and 6. there is then given a measure of theenergy of the lecher system, The indicator rod, when it 4is dimensionedwith a relatively small diameter takes but little energy from the lechersystem since it must be heated only to the vicinity of thosetemperatures at which a change of color takes place. These temperaturesare, however, comparatively low if compared for example 'with those ofan incandescent filament. As the above mentioned examples oi' heatindicator colors show, even temperatures up to 50 are sulcient. Toattain the object of still less energy being taken by the4 indicator rodfrom the lecher system it can be preheated by radiated heat or 'hot airup to the vicinity of the color changing point. The indicator rodaccording to the invention can naturally also serve to determine thecurrent loops. To this end it is only necessary to determine the centerbetween the points 9 and 9 at which the same color change takes place;there is then at this center point a current loop if the points 9 and 9directly follow eachv other with respect to the change of color.

A further possibility for determining the energy oi' a lecher system isshown in Fig. 3. Accoromg to this, the indicator rod 3 carries at itstwo ends cooling v anes Il and ll which are to cause a cooling of therod at the two ends. There takes place on the rod a temperaturedropwhich is characterized by twd points I2 and Il which are locatedsymmetrically to thev lecher wires I and at which the rod changes itscolor.' om the distance between the points I2 and I3 there can bedetermined the steepness of the tempera- Under certain circumstances, itwill be advisable to apply a number of indicator colors on' theindicating rod in order to c heck measurements which areagiven by thechange of one color, with other colors, or in order to be able to choosefrom diierent possibilities that one which is most ./I have herein shownand particularly described certain embodiments of my invention andcertain methods of operation embraced therein for the purpose ofexplaining its principle and showing its application but it will beobvious to those skilled in the art that'many modifications andvariations are possible and I aim, therefore, to cover all suchmodifications and variations as fall within the scope oi my inventionwhich is defined in the appended claims.

What I claim as new and desire to secure by Letters Patent 'of theUnited States, is:

1. An indicating device for a lecher system comprising an electricallyconducting rod adapted to bridge over the lecher system coated with amaterial having the property of varying in color in accordance withvariations in temperature, and having cooling ns attached at the endsthereof to produce points of color change, the positions of which on therod are dependent upon the current therein. y

2. An indicating device for 'a lecher system comprising an electrieallyconducting rod adapted to bridge over the lecher (system, coated with amaterial having the property of varying in color in accordance withvariations in temperature. and h ving means in contact with the ends of`the'rod fo cooling the same to produce points oi color change. thepositions of which on the rod aredependent upon the current therein.

3. A current indicator comprising an electrically conducting rod,'acoating thereon compris- .ing material having the-property of varying incolor in' accordance with variations in temperax.

ture. and means for cooling aportion oi' the rod to produce a Apoint ofcolor change, the position of which o n the rod is dependent upon thecurrent therein.

n Q HANS BoERscH.

